_test_multiprocessing.py 文件源码

def tearDownClass(cls):
        # only the manager process should be returned by active_children()
        # but this can take a bit on slow machines, so wait a few seconds
        # if there are other children too (see #17395)
        t = 0.01
        while len(multiprocessing.active_children()) > 1 and t < 5:
            time.sleep(t)
            t *= 2
        gc.collect()                       # do garbage collection
        if cls.manager._number_of_objects() != 0:
            # This is not really an error since some tests do not
            # ensure that all processes which hold a reference to a
            # managed object have been joined.
            print('Shared objects which still exist at manager shutdown:')
            print(cls.manager._debug_info())
        cls.manager.shutdown()
        cls.manager.join()
        cls.manager = None